There has hitherto been known a power transfer device that includes: a torque converter (fluid transmission device) that includes a pump impeller connected to an engine (motor) and a turbine runner connected to an input shaft of a speed change mechanism; an oil pump driven by power from the engine; a chain system (chain drive mechanism) that includes a drive sprocket coupled to the pump impeller of the torque converter via a torque converter sleeve, a driven sprocket coupled to an oil pump drive shaft, and a chain wound between the drive sprocket and the driven sprocket; a stator shaft that supports the input shaft of the speed change mechanism; a torque converter housing that houses the torque converter; and a center support which is attached inside a transmission case that houses the speed change mechanism and to which the stator shaft is fixed (see Patent Document 1, for example).
In the power transfer device, the drive sprocket of the chain system is rotatably supported by the stator shaft, and the pump impeller of the torque converter is rotatably supported by the torque converter housing via the torque converter sleeve. The power transfer device additionally includes first, second, and third oil passages that supply oil (working oil) from an oil passage formed in the center support to the torque converter. The first oil passage is formed inside the input shaft. The second oil passage is constituted of a space defined by the input shaft and the stator shaft. The third oil passage is formed on the outer peripheral side of the drive sprocket so as not to interfere with the track of the chain, and composed of an inlet flow path that extends in the axial direction from the center support, a communication flow path formed in the torque converter housing, a hole and a groove formed in a bearing between the torque converter housing and the torque converter sleeve, an outlet flow path formed in the torque converter sleeve, and so forth.
There is also known a power transfer device that includes: a torque converter that transfers power from an engine (motor) to an input shaft of an automatic transmission; an oil pump driven by power from the engine; an oil pump drive mechanism (chain drive mechanism) that includes a first sprocket (drive sprocket) coupled to an impeller shell (pump impeller) of the torque converter via a torque converter sleeve, a second sprocket (driven sprocket) provided on an oil pump drive shaft, and a chain wound around the first sprocket and the second sprocket; a stator shaft that rotatably supports the input shaft of the automatic transmission; and a unit housing that includes a torque converter housing that houses the torque converter, a cover to which the stator shaft is fixed, and so forth (see Patent Document 2, for example). In the power transfer device, the impeller shell (torque converter sleeve) of the torque converter is rotatably supported by the stator shaft via a first bush (bearing), and the first sprocket of the oil pump drive mechanism is rotatably supported by the stator shaft via a second bush (bearing).
In addition, there is also known a power transfer device that includes: a bush disposed between a tubular portion of a rotary member coupled to a converter cover of a pump impeller and a projecting portion of a transaxle case that serves as a stationary member so as to seal a pressurized oil passage; a drive-side sprocket of a transmission mechanism coupled to the outer peripheral side of an intermediate portion in the tubular portion of the rotary member; and a bearing disposed on the outer peripheral side of the bush and the projecting portion of the transaxle case so as to rotatably hold the drive-side sprocket (see Patent Document 3, for example). In the power transfer device, the drive-side sprocket includes a disk-shaped portion spline-fitted to the tubular portion of the rotary member, and a tubular portion that extends in the axial direction from an outer end portion of the disk-shaped portion, and the bearing is disposed between the tubular portion and the projecting portion of the transaxle case.